The couple announced their engagement in December.
Stone got engaged to Dave McCary in December with a unique ring. A source previously told ET that Stone's engagement ring boasts an 8mm untreated Akoya pearl surrounded by a diamond snowflake motif and features solid 18k gold and 0.37 carat diamonds.
In the interview with Witherspoon, though, Stone appeared to be sporting a solid gold band, perhaps indicating that she and McCary, whom she began dating in 2017, had already tied the knot.
Also lending to the possibility that the pair already said "I do" is the conversation Stone had with Witherspoon and fellow guest Dr. Harold Koplewicz of the Child Mind Institute, during the chat.
While the trio was discussing anxiety, Koplewicz joked, "If you marry an anxious man, you’re going to have to know me the rest of my life."
"Thankfully, I didn’t do that," Stone responded.
ET has reached out to Stone's rep for comment.